1. Field of the Invention
The invention relates to an internal combustion engine, comprising an engine block, a crankshaft rotatably journalled in the engine block and an auxiliary drive transmission mounted at one side of the engine block. The transmission has an input shaft with an input gear wheel meshing with an output gear wheel driven by the crankshaft and a first output shaft driven by the input shaft for driving at least one auxiliary unit.
2. Background of the Invention
Usually, in common internal combustion engines, auxiliary units, such as water pumps, generators, pumps for power steering, and air conditioning, are driven by the crankshaft via pulleys or gear wheels mounted on an end portion of the crankshaft extending outside of the crankcase. The same is true for engine components, such as camshafts and fuel pumps, which often are driven via a toothed pulley and belt at the front end of the engine block. These auxiliary units, and the driving assembly at the front end of the engine, increase the total length of the engine and require space in the engine compartment. Basically, this is not a problem in vehicles having longitudinally mounted engines. But, when it comes to transverse mounted engines, space is more limited, particularly in those having more than four cylinders. For example, those with six cylinders are usually V-engines.
It is known in the art to reduce the space requirements of an in line engine, e.g., an in-line, six-cylinder engine, by arranging an auxiliary drive transmission (transmission heretofore refers to auxiliary drive transmission) for auxiliary units at one side of the engine. For instance, DE 2 153 773 discloses an in-line, six-cylinder engine having a side-mounted transmission with a single output shaft drivingly connected to a fuel injection pump and an air compressor. The generator, however, which preferably operates at a higher rpm than the fuel injection pump, is driven in a conventional manner by a separate pulley and belt transmission in the front end of the engine block.
Drawbacks of prior approaches are overcome by an internal combustion engine with an engine block, a crankshaft rotatably journalled in the engine block, and a transmission mounted at one side of the engine block. The transmission has an input shaft with an input gear wheel meshing with an output gear wheel driven by the crankshaft and a first output shaft driven by the input shaft for driving at least one auxiliary unit. The transmission has a second output shaft with the first and second output shafts being driven with different speeds of rotation from the input shaft. Furthermore, a first and a second gear wheel on the input shaft meshes with a first and a second output gear wheel on the first and second output shafts, respectively, with the first and second input shafts having a common axis.
An advantage of the present invention is an internal combustion engine which is short, for example, a five-cylinder in-line engine with auxiliary devices according to the present invention is no longer than a conventional, previously known, four-cylinder in-line engine with auxiliary devices.
More specifically, an advantage of the invention is to achieve an internal combustion engine which has a compact transmission design and drives at least two auxiliary units, or engine components, at different input speeds.
A further advantage of the invention is to achieve an internal combustion engine with a side mounted transmission which is particularly suitable to enable driving one auxiliary unit by another auxiliary unit, e.g., driving an air conditioning compressor by an integrated starter/generator when the engine is not running.
These and further advantages are achieved according to the invention by virtue of the fact that the transmission has a second output shaft, the first and second shafts being driven with different speeds of rotation.
In a preferred embodiment of the present invention, the second output shaft is hollow and the first output shaft extends through the second output shaft. Preferably, the first output shaft is then driven at higher speed than the crankshaft by a first smaller gear wheel on the first output shaft. Further, the first output shaft is drivingly connected to an integrated starter/generator at one end and an air conditioning compressor at the other end while the second output shaft is driven at a lower rpm than the crankshaft by a larger gear wheel on the second output shaft and is drivingly connected to one or two camshafts. By mounting the smaller gear wheel via an. engageable and disengageable one-way coupling on the first output shaft, the starter/generator is capable of, with the one-way coupling disengaged, driving the compressor when the engine is not running.
Other advantages, as well as objects and features of the present invention, will become apparent to the reader of this specification.